Running Cs-Cart Mv On A Sub Folder

I want to run CS-cart MV on an existing domain that is running a different software. My questions are:

1. I already have CS-Cart MV running on it's own VPS partition on a siteground cloud account. How do I transfer to a sub folder?

2. Is there an easy to integrate (and use) tool that will allow my users to stay signed in across both the CS-Cart MV software and the original e-comm software?

3. Is the above too complicated? is it possible to keep both websites running on seperate partitions on my cloud account and just use some kind of DNS config to make the cs-cart appear in a sub-folder?

NOTE - I do not want to run a sub-domain. My preference is sub-folder.

something like 2 storefronts ?

Check this