The most common way of obtaining publicly available applications for SharePoint Online is by downloading them from Microsoft Store.
Step 1. Getting the application
1) Open Microsoft Store by going to “add an app” in Site Contents:
2) In SharePoint Store use search to find PDF Share Forms Cloud app:
3) Click on the PDF Share Forms Cloud to view details:
Note: App Catalog site is required to add PDF Share Forms Cloud app to your SharePoint site. App Catalog site is used as storage for applications in your SharePoint Online sites. If "Request Approval" link is not available, please check that you have App Catalog site. Additional information can be found here.
Step 2. Installation
1) To add an application to your SharePoint site, first you need to request an approval from tenant administrator. Click on “Request Approval”:
Click on “Request” button.
2) Tenant administrator can approve request by clicking on appeared request in “App Requests” section of App Catalog site:
Click “Approve” button to allow installation for this application:
Note: once app is trusted, you need to return back to Microsoft Store to continue installation. Please look at Step 1 for additional references about finding PDF Share Forms Cloud app in Microsoft Store.
3) Now you can add PDF Share Forms Cloud application by clicking on “Add It” button in Microsoft Store:
4) Once clicked, application will require confirmation – click on “Continue” button:
5) Make sure that check box (Add this app to site) is checked and app will be added to the site. Now you can return to your SharePoint site by clicking on “Return to site” button.
6) Click on “Trust It” button to allow application to add necessary files to your SharePoint Online site:
7) You will find new application in Site Contents of your site:
It might take a several minutes to finish installation: