GlasierXplor

Edit: I see that you also updated with your machine specs.
With those specs, I highly doubt you will want to run anything heavy (i.e. a GUI), and you will have to get comfortable with a Linux command line. Virtualisation is out of the question since the specs are a bit too low. Containerisation I would say is still possible (e.g. Docker). For the two things that you want to do, I will also say that you may not be able to do anything much more than the two you have stated. Maybe a small web server is still possible, but I won't count on it.
 
If you want a virtualisation server, try Proxmox (free, open source) or VMware ESXi (1 server, free).
 
If you are comfortable with a server OS (i.e. command line), try Ubuntu server.
 
If you prefer a desktop, e.g. desktop OS also shares a NAS, while hosting other applications, try Ubuntu Desktop or any of its lightweight derivatives (with minimal installation, strips most of the bloatware). You might have a better experience because your system resources will be used on the applications instead of trying to run Windows smoothly.
 
Ubuntu tutorials are quite easy to find, just need to keep in mind some changes that occurred between Ubuntu 16.04 and 18.04 (hint: following an Ubuntu 18.04 or newer tutorial should be safe if you download the latest Ubuntu LTS release).

Hi, I am here to share how Office 2016 can be installed on Ubuntu 18.04LTS using PlayOnLinux (I tried on Kubuntu 18.04.4LTS, and elementaryOS 5.1.5). But the main reason I decided to post this here because I need help with PlayOnLinux scripting (which until now I still don't understand).
 
I have previously made a post about this on the PlayOnLinux forum (to no avail, but someone managed to get it installed based on my guide so I am happy ).
 
Steps
Install PlayOnLinux (according to instructions on playonlinux.com for the latest version, which is needed for WINE 4.15) and required dependencies:- sudo apt-get install playonlinux winbind smbclient gnome-disk-utility wine-stable:i386  
Using POL, install WINE version 4.15 (32-bit). Download Office 2016 from office.com (offline version was the only one that worked for me. The IMG contains both x86 and x64 installers). After downloading it, mount the IMG file using gnome-disk-utility. On POL, Click Configure > New to create a new drive 32-bits Windows Installation Wine Version 4.15 Name the drive as you like. I named it "Office2016" Select the new drive > Install Components. Install "msxml6" and "riched20" Select "Wine" tab > "Configure Wine" "Applications" > Windows version = Windows 7 "Libraries" > set the following:- riched20 (native, builtin) msxml6 (native, builtin) Exit "configure wine", open "Registry Editor". Navigate to "HKCU\Software\Wine", and Right click on "Wine" > New > Key. Rename new key to "Direct2D". Right click on "Direct2D" > New > DWORD Value. Rename new DWORD to "max_factory_version". Ensure that "max_factory_version" is set to 0. Close the Registry Editor. On the configure window > Miscellaneous > "Run a .exe file in this virtual drive". Select the "setup.exe" that was in the IMG file that you mounted back in step 4. The installation should run normally, but the installation window will be half blank. If you have an indicator applet, the Office logo should pop up there. Else Wine should spawn a system tray for you. Click on this to spawn the progress  window in the bottom right. After installation completes, use the "kill all processes" in the POL configuration window. Create application shortcuts as needed (in the "General" tab). Copy "AppvIsvSubsystems32.dll" and "C2R32.dll" from <office2016-root>/Program Files/Common Files/Microsoft Shared/ClickToRun/ to <office2016-root>/Program Files/Microsoft Office/root/Office16/ Start any of the Office applications. It will prompt that Office is not activated. DO NOT use the license key that came in the box of the Office 2016 -- it will not work. Instead, go back to office.com > My Account > Service & Subscriptions . Under the "Install" link there is a "Show Product Key" link. Clicking on it reveals a product key different from the one you have in the box. Use this license key to activate Office instead. Once done, Office will be activated and can be used.