Alternatively, the following online tool can be used to generate CSR: https://decoder.link/csr_generator. Please make sure to save both CSR and the Private Key codes, as the latter one will be required for the certificate installation process on the server.
If you are activating a Multi-domain certificate, and your server does not allow you to generate a CSR for multiple common names, activate your certificate using just one common name. You will be able to add all required SANs through your Namecheap account during the activation process.
If you're using hosting services from Namecheap, click here for instructions.
Please note: Normally, a dedicated IP address is required for SSL installation. However, you may install your SSL certificate on a shared IP address using the Server Name Indication (SNI) protocol extension available in your cPanel. You can learn more about the differences between a dedicated IP and SNI technology in the SNI Technology guide. When contacting our support team regarding this issue, please specify whether you wish to order a dedicated IP address or have your SSL installed on a server's shared IP.