In order to link an accountant to your business account, they first must have a Microkeeper account of their own.
If your accountant has not already done so, request that they register with Microkeeper and provide you with their username that they use to login with. Register Microkeeper Account Link.
In your business account, go to Manage > Linked Users > Click Add User, enter your accountants username.
When your accountant logs in to their account, they will go to Manage > Linked Users and select to login to your business. Note: Your accountant will have full access to your account.