If you don't see the button on the policy object, ask your admin to follow these steps:
If the Policy opens as a Lightning record page (most common):\\
1. Open a Policy record, click the gear (top right) > Edit Page\\
2. Select the Highlights Panel at the top of the page\\
3. In the right panel, find the Actions list and click Add Action / edit the action list\\
4. Add "Create Ascend Subscription", then Save and Activate
If they use a classic page layout instead:
1. Setup > Object Manager > Policy > Page Layouts > open the layout in use\\
2. Click "Mobile & Lightning Actions" in the palette\\
3. Drag "Create Ascend Subscription" into the Salesforce Mobile and Lightning Experience Actions section, then Save