When visiting your Soapbox Engage base URL, you'll likely see an error message with the following title.
404 - Component not found
This is expected, since the base URL for your Soapbox Engage account is unlikely to be associated with a Soapbox Engage page (i.e. a Donations app page). For nearly every Soapbox Engage page, you'll have a "slug" appended to the end of the base URL, which takes you to a specific Soapbox Engage page.
For example, assume your Soapbox Engage base URL is https://engage.example.com. This page is unlikely to load anything other than the 404 error message above. To view a page, you'll need to add the URL slug to the end of the page.
For example, a donation page you created might have a URL like https://engage.example.com/donate, where "donate" is the URL slug. In this example the base URL is https://engage.example.com and the URL slug is "/donate".