Problem with 2.2 version in Linux

I have tried to install the LibreCAD v2.2. Even though  I typed the below command into terminal....

sudo add-apt-repository ppa:librecad-dev/librecad-daily
sudo apt-get update
sudo apt-get install librecad

And I still got the version, 2.1

My current Linux OS is Ubuntu 20.04 [HOW TO GET LC 2.2 (alpha) FOR THE SAME???]

The PPA's are not maintained for a while, you can't get a newer version than 2.1 from there.
The only way to get latest LibreCAD on Linux is to build from source currently.

https://librecad.readthedocs.io/en/latest/appx/build.html

 I seriously need to learn C++ for ONLY LibreCAD??

I am using lots of Open-Source software of all 'Alternatives' (Graphic Design, Office-suite, Rendering) which works very perfectly (for me) without having Coding experience but this Open-source CAD software really annoys me, every single day comes with new surprises. 

I was just thinking that I would contribute a COMPLETE LIBRECAD TUTORIALS series to the community but HOW CAN I??
Now need to wait until I become a developer.

It does not need to be a developer to build the program. I did with limited knowledge following the build instructions.
I suggest you go through the Wiki and manuals to see what is already existing. Then there is room for improvement and additional tutorials. Zulip Chat will also be helpful to connect with active people on the project (code, documentation, etc.)

VyasG_007 wrote

I am using lots of Open-Source software ... [but LibreCad] annoys me, every single day comes with new surprises.

I was just thinking that I would contribute a COMPLETE LIBRECAD TUTORIALS series to the community...

I totally agree there is something unexpected about the user interface but I couldn't describe it and after I did the Carport Tutorial most things seemed natural. Given your experience with other graphics applications, documenting your interface expectations as a new user would be useful before referring to the manuals and tutorials.

In my view between the LibreCAD User Manual in preparation and the Dummies Guide I think there are enough manuals but more tutorials would be useful. Contributions are always welcome in whatever format you are happy with but consider contributing to the existing documentation.

I already go through the user manual.

User Manual only teaches, how to use the tools, but I can teach practical approach of those tool in real-life situation. So it is required to combine the knowledge of two minds, Developer and CAD user, because each one has the proficiency to their related profession and knows 'how it should works'.

For experience CAD user like me who are working with multiple CAD applications (used three 2D CAD softwares and four 3D CAD Modeling softwares), LibreCAD has a very simple User Interface with complicated command's action (the only draw back of this software at some extent) and some feature which Commercial CAD packages do not have, which is also remarkable thing to get involved into it because I am directly related to target audience of this software.

Hi MrCAD

Did you get LibreCAD 2.2 installed on your system? If not I would like to help you get it done and find out how we can make it easier for the next person who tries.

Regards, Duncan