If you open a design document containing fonts which are not installed on your computer, you will see a Missing Fonts message upon opening the file. If you proceed without resolving the missing fonts, a default font (usually means a random one) will be substituted in.
As you image, the appearance of the document will be affected, and that's why we recommend resolving the missing fonts. Today we announce that the Font Auto Activation supports Affinity Publisher (Beta)! When you open a Affinity Publisher file and encounter a message like this, try using RightFont to resolve the missing fonts automatically.
Enabling Font Auto Activation for Affinity Publisher
Open Preferences window in RightFont, and switch to Auto Activation tab. Click the Affinity Publisher icon to turn this feature on or off. Please note, you won't see the Affinity Publisher if you did not install Affinity Publisher on your computer.