You can create as many separate account as you want, just need different credentials.
You can even sponsor all your alt accounts with your own referral code.
It is funny because i just had a talk with @Will C. about that last hour on discord. He told me a Concierge support once replied him that in the future it would be possible to lend a ship from one account to another.
Right now this is a major question for me, between multiple accounts and multiple game package within an account, packages which are supposed to grant multiple character slots in a single account. I will be waiting for an official answer before spreading my fleet between all my accounts if you can only play with a character slot at a time per account.
You can make as many alt accounts as you want. Though I would imagine managing them past a few would be a nightmare.
I made some accounts for my family, and should probably make a couple more for myself.