If you are unable to add photos to the Sera Tech App, this is usually an issue with the general Settings on your iPad.
From the Settings app, find the Sera Tech option. Clicking on the Sera Tech option and look for Photos. The options under Photos will be different depending on the iOS version that you are using, but you will want to make sure that you don't have the option that says None selected. If you do, you will want to click Photos and select another option. You can give the Sera Tech app permission to view all or some photos that you select.
Note: If you don't see the Photos option at all within your Settings, navigate back to your Sera Tech App and select the Add Photos button from your Photos and Documents area. This should provide a pop-up for selection on how you would like to share photos with the Sera Tech App.