How to Install an SSL Certificate on IIS 10 Manually

Purchased and downloaded your certificate from your certificate provider like Godaddy, Digicert, SSL.com etc..

Convert your .crt file to a .cer file

  1. Locate your downloaded .crt file, and double-click to open it.
  2. Select the Details tab, and then the Copy to File button.
  3. Select Next in the Certificate Wizard.
  4. Select Base-64 encoded X.509(.CER) and then select Next.
  5. Select Browse, locate where you want to save your .CER file, and type in a name for your certificate.
  6. Select Next and then Finished.

Copy your certificate files onto the server

  1. Find the directory on your server where certificate and key files are stored, then upload your intermediate certificate (gd_iis_intermediates.p7b or similar) and primary certificate (.cer file that you just converted) into that folder.

Add a Certificate Snap-in to the Microsoft Management Console (MMC)

  1. Click on your Start Menu, then click Run.
  2. In the prompt, type mmc and click OK.
  3. Click File, then click Add/Remove Snap-in.
  4. On the new window, click the Add button.
  5. On the new window, select Certificates and click Add.
  6. Select Computer account for the snap-in and click Next.
  7. Click Local computer and click Finish.
  8. Click Close on the Add Standalone Snap-in window.
  9. Click OK on the Add/Remove Snap-in window.

Import the Intermediate SSL Certificate

  1. In the MCC Console, click  to expand Certificates (Local Computer).
  2. Right click on the Intermediate Certification Authorities folder, hover over All Tasks and click Import.
  3. On the new window, click Next.
  4. Click Browse, find your gd_iis_intermediates.p7b intermediate certificate file and click Open.
  5. Click Next, verify that the certificate information is proper and click Finish.
  6. Close the the import was successful notification.

Install your SSL certificate

  1. Click on your Start Menu, then click Run.
  2. In the prompt, type inetmgr and click OK to launch the Internet Information Services (IIS) Manager.
  3. Under the Connections panel on the left, click on your Server Name.
  4. In the main panel under the IIS section, double click on Server Certificates.
  5. Under the Actions panel on the right, click Complete Certificate Request.
  6. On the new window, click  to browse, find your previously uploaded primary certificate file and click Open.
  7. Add a Friendly name to easily identify this certificate in the future.
  8. In the certificate store option, select Web Hosting and click OK.

Bind the SSL certificate

  1. Under the Connections panel on the left, click  to expand the Sites folder.
  2. Click the Site Name that you plan to install the SSL certificate onto.
  3. Under the Actions panel on the right, find the Edit Site section and click Bindings.
  4. On the new window, click Add and fill out the following information:
    • Type: select https.
    • IP Address: select All Unassigned.
    • Port: type in 443.
    • Host name: leave this empty.
    • SSL Certificate: select your recently installed SSL.
  5. Click OK to confirm, then Close for the Site Bindings window.

Restart IIS (optional)

  1. Under the Actions panel on the right, find the Manage Website section and click Restart.

Ref: Manually install an SSL certificate on my IIS 10 server | SSL Certificates – GoDaddy Help CA