To set up a dynamics 365 online trial, follow the steps:

Step 1:

Click here to start with a trial online setup. Then click on the “try for free”.

Step 2:

Instead of typing in the email address. Leave it blank and click on Start your free trial.

Step 3:

A new line will pop up. Marked in the red rectangle. Click on “Click here”. You will be navigated to a new page where you would have to start adding information.

Step 4:

Once registration is done. Click on Get Started. You will be navigated to the admin center where you would have to create a new environment.

Step 5:

Wait for the instance to get ready. Once it is prepared select the environment and click on the open environment.

Select the app. For now, select Dynamics 365 – custom.

You can now start using your trial instance.
Note: The trial instance expires after 30 days. These are just built for demonstration and learning purposes.