adobe stockk multiple account creation

You can contribute both types of assets in one single account. There is no need to use different accounts for this, and as @Jill_C and @daniellei4510 have told you, it is not possible to create more than one contributor account. 

As for your other question: you seem to be an absolute beginner, or you would not ask such a general question. This is an Adobe provided forum, we won't make advertizing for products that are not Adobe created tools, except if there is no Adobe solution available. You can use Adobe Firefly for what you want to do, but be aware, that you will need to edit your assets and correct rendering errors before submitting. This is also true if you use third party tools, btw.

You need to read all Adobe guidelines carefully before opening an account and starting to upload. Multiple accounts are expressly forbidden, which you would have learned by reading the guidelines.