The operating system my web server runs on is (include version):
My hosting provider, if applicable, is: InfinityFree
I can login to a root shell on my machine (yes or no, or I don’t know): IDK
I’m using a control panel to manage my site (no, or provide the name and version of the control panel): cPanel (i think)
The version of my client is (e.g. output of certbot --version or certbot-auto --version if you’re using Certbot): IDK
I was trying to install the ZeroSSL (from web client) certificate vía DNS and the dns records worked fine. Now, at the time I tried to upload the keys, InifnityFree says that doesn’t support keys bigger than 2048 bits. So I was wondering how do I specify create the Private Key in 2048 bits to make sure the keys and certificates upload successfully and finally get my SSL/TLS encryption for my web.
It does, and it is documented - see the "Important" notice and the paragraph above it of the "How to use" section. Effectively you just need to use CSR Generator first and choose 2048 bits key, and then use that CSR with the SSL Certificate Wizard. Please note that the key generated by the CSR Generator will be your "domain key" - there will be no key shown at the last step of the SSL Certicate Wizard in this case.