The SharePoint standard connector will work for customers with simple needs for collaboration. There is a Teams integration available soon, and I will write about that once it is released in Europe.
Start off by creating a new site in SharePoint. I prefer to create everything on a new site, because then we can control the site better.
Copy the URL of the site before you move on back to CRM.
I prefer to create folder for the entities Account and Opportunity. Remove all the other entities in the simple demo (not that it really matters).
I prefer to have a structure based on account. This will create opportunity folders bellow the account folder.
If it all worked out, you can now open an opportunity with account connected.
Opening the document on opportunity will now give full access to storing documents in SharePoint. I will write an extended blog about considerations to make when integrating this to Teams later.