How to combine 2 projects into one?

Hi there folks,

Not sure if I use the right lingo here, but here is what I’m trying to achieve.

I have created a landing page from blank that has subscribe button, few boxes etc.

I want now to clone Dashboard templates with sign up, login, profile, billing etc.
I have found few suitable ones like Ektora and the ones from Memberstack, but I’m trying to bring the clone and my landing page together.

How do I merge somehow the clone from Ektora/Memberstack into my existing project?
Should I move the files into my landing page?
Should I use subdomain for the dashboard and have 2 seperate projects for landing page and for dashboard?

Thanks in advance.