No. Without a registered business, you cannot use Malt.
A registered micro-enterprise, sole trader or company can sign up. Then submit your legal documents so you can invoice and get paid. The list depends on your country: which legal documents apply in my country.
If your registration is still in progress, Malt releases payment for your projects once these documents are validated.
You are starting in Switzerland
In Switzerland, the AHV certificate is issued only after you have a contract with a client and your first invoices. You cannot obtain it before you start.
To start on Malt, upload a sworn statement instead of the certificate. You then have 90 days to obtain the official AHV certificate and upload it on Malt.
The other requested documents are listed in Which documents do I provide in Switzerland?.