Domain masking issue

This issue has probably been answered already and I’ve found a few topics on it which I’ve tried their solutions but it’s not working for me. I’m not sure whether it’s because I have something already entered in the htaccess file or not.

Basically, I have a domain that I’ve bought from Godaddy (say https://domain.com). And my site is hosted on Hostgator in a subdirectory (e.g. https://example.net/mysite). I want to mask the site by the domain that I’ve bought from GoDaddy.
So that only https://domain.com or https://www.domain.com shows up in the address bar. But all subfolders and categories appear after the domain.com

So if I have
https://example.net/mysite/blah-blah01

I want it to look like this:
https://domain.com/blah-blah01

Currently the site address is correctly being masked but only the home page. All other pages can only be access by the original site url or else if I use the domain.com/blah-blah01 for e.g. I get a 500 Internal Server Error

So, is there a way to mask a domain with all the subfolders and categories too?

This is what I have on the htaccess file:
# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /mysite/
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /mysite/index.php [L]
</IfModule>

# END WordPress

RewriteEngine On
RewriteCond %{HTTP_HOST} ^domain\.com$ [OR]
RewriteCond %{HTTP_HOST} ^www\.domain\.com$
RewriteRule ^/?$ “http\:\/\/example\.net\/mysite” [R=301,L]

Any idea what I’m doing wrong?