The 'Activate Account' button link should work fine as long as the following variable has not been changed in the app editor.
{{customer.account_activation_url}}
To ensure it’s set as it needs to be, please follow the below guide.
Login to OrderlyEmails (Shopify admin -> Apps)
Click the "Customize" button on your design
In the editor, select the "Customer invite" email
Click on the "Button" section
Make sure that the "Links to" field has: {{customer.account_activation_url}}
Once done, click "Export to Shopify" and copy/paste over the new email code.
Once this is all set, then the link will use the correct URL for the customers to confirm their account.
Note: Test emails will not have a "working" link, as those are generated by Shopify for each email sent.
Having more questions? No worries, get in contact with our support team using the message icon on the lower right corner of this page.