(Note: I'm not a lawyer, but this is my understanding based on my experience)  A human being will need to sign on behalf of the LLC and that human will need to have the authority to sign. 

Once the lease is signed, I go to the bank and open a new security deposit account, and then the bank provides account number, which I then manually enter in the lease and have the tenant sign the lease again.Any guidance on avoiding the hassel of having to sing the lease twice lease?

They sign into their own accounts, and the TV automatically signs them out of all accounts on their check-out day.

So you may not NEED a lease signed for your primary residence already, especially since that's a lot of stress to find a new tenant and have a lease in place while you're under contract on another home.

Furthermore, there is likely an Affiliated Business Agreement Disclosure that you'll need to sign. 

We already signed the purchase agreement several months ago...it has been on hold while they mitigated a pest control issue that has taken 2 months.If it's that important, make it part of your purchase agreement.

Quote from @Philip Jones: Hey guys I am a Landlord out of Metro Detroit area.

I had been a tax client of Anderson in prior years, but never signed up for any of their client programs.

Quote from @Collin Hays: I don't manage short-term any more, but can't you include this in a written rental agreement that the guest signs at the time of booking?

@Matthew Mclean It's totally your call but my advise is to read the contract that they'll make you sign. Fully