When you have a document shared with you there are multiple ways to first access it.

From an email link

1. Navigate to your email inbox
2. Click on the 'Open Document' link within the email
3. You will be taken to Drawboard PDF
4. Sign in or sign up to a Drawboard Account
5. You will then be granted access to the document

From a share link

1. Click on the link that has been sent to you
2. You will be taken to Drawboard PDF
3. Sign in or sign up to your Drawboard Account
4. You will then be granted access to the document

Once you have first accessed a shared document it will then appear in your dashboard, where you will be able to access it whenever you like.