How do I upload a couple documents that I can link to them in the agreement or email?
In the same way you have the two Travel Insurance docs uploaded...
Now I think you just click a little up[load button when editing a template
Can we create a custom template? This is something different than just a legal agreement or email template. This would be a few documents I would like to create a hyperlink to, FROM email, legal agreement, etc.
Yes, do that under your global Files. Click the Account button drop-down (top right) and Files. There you can upload any type of file. Once uploaded, the button on each file will give you a "copy link" you can use in any email or renter agreement. BlueMtn is also correct that you can embed/upload inside any email or renter agreement at that moment.
