Hello Yucel,
You will unlikely to integrate it without conflict because we already use bootstrap which is became front-end framework.
Anyway in theory you may remove bootstrap styles include and include include UlKit framework (on this step the template will get mess).
After you should replace all bootstrap references with UlKit tags and adjust it to UlKit api. Finally you may achieve a good result.

I recommend agains using UlKit and choose bootstrap, UlKit is too heavy with JavaScript and not so popular as bootstrap.
Good luck!

John