Setting Single Login across 2 Sites

I have a website wich uses wordpress in its root and I have a plugin called awesome media gallery that installs a community that has its own unique set of accounts.

I have installed site #1 WordPress in https://www.site.com/ (uses a modified theme) and its Multisite
For site #2 Community I installed it in https://www.site.com/community

Both wordpress and community are installed at the same database..with wordpress having the prefix (wp_) and community with (mk_)

Now I want both sites to use the same login.
How do i do this? I know the reference links I provided below might not work since the awesome media gallery wp plugin is a different framework. Its not wordpress. How do I go about this? Thank you.

https://fullthrottledevelopment.com/setting-a-single-login-across-wp-wpmu
https://www.kiranthomman.com/setting-single-login-across-multiple-wordpress-27-installs-using-a-single-domain/