In Android 11, to install a CA certificate, users need to manually:
-  Open settings. 
-  Go to 'Security' or 'Password & security'. 
-  Go to 'Encryption & Credentials'. 
-  Go to 'Install from storage'. 
-  Select 'CA Certificate' from the list of types available. 
-  Accept the warning message (install anyway). 
-  Browse to the certificate file on the device and open it. 
-  Confirm the certificate install. 
OR
-  Open settings 
-  In the search box, search for - cert
 
-  Select 'CA Certificate'. 
-  Select 'CA Certificate' again. 
-  Accept the warning message (install anyway). 
-  Browse to the certificate file on the device and open it, usually it will be in your downloads folder.. 
-  Confirm the certificate install. 
OR
-  Open settings 
-  In the search box, search for - install certificate from storage
 
-  Select 'Install certificates from storage'. 
-  Select 'Install certificates from storage'. again 
-  Select 'CA certificate' from the install a certificate menu. 
-  Accept the warning message. 
-  Browse to the certificate file on the device and open it, usually it will be in your downloads folder.. 
-  Confirm the certificate install.