MultiTheme Process help

I am at a bit of a loss and I have searched here and read quite a bit over the past few days but I am having issues with my own process.

With my website there are 3 “sites” the hub page which will be html based and will link to 2 separate WP themes.

Now I have put WP into it’s own sub-directory and installed WP theme 1 into that directory as well. I’m not sure if that was incorrect from the get go, though that was my early process to get the index.php file empty and use for the hub page.

Next I finished the process of installing it as a multi-network and things seem fine so far as I’ve hopped back and forth looking at each of the dashboards etc.

However I have not fully installed theme 1 yet and have yet to add in theme 2. Again not sure if this was an error and at least one of the themes has to be installed first.

My hopes is to connect the two themes with same user logins (preferable 1 time login) and hope that the two templates can co-exist with updated comments posts etc.

Thing is now as I follow the step by step of theme 1 for the full install a lot of options are not available so I cannot fully install the theme.

I’m open to reinstall WP etc.

Should I fully install theme 1 and then make it multi-network?

And I’m at a loss with installing even the second theme as I can’t seem to find anywhere how to do that (tutorial) once I’ve got the multi going?

I did get to the point of creating 2 sub-directories within the multi dashboard.

Any links or help would be great, I’ve followed these ones so far:

https://codex.www.ads-software.com/Before_You_Create_A_Network
https://codex.www.ads-software.com/Create_A_Network
https://www.ads-software.com/support/topic/multiple-themes-one-site?replies=14
https://www.elegantthemes.com/blog/resources/the-complete-guide-to-creating-a-wordpress-multisite-installation

I am a newb to WP and just 3 days ago wouldn’t of understood exactly what I just said so any help I’d appreciate,

Thanks.