It is not a request FOR form 4564 ... it is a form 4564 which is requesting more information ... read the notice carefully and respond appropriately and timely. If you are in an audit and they are asking for a lot of information then you may wish to seek professional guidance from a local tax professional or tax attorney ... this can be very serious depending on what they are asking for.
(what the letters from the IRS mean)
I GOT A LETTER FROM THE IRS
https://ttlc.intuit.com/questions/3605673-i-got-a-letter-or-notice-from-the-irs
I AM BEING AUDITED
If you purchased Audit Defense:
https://ttlc.intuit.com/questions/2924451-i-bought-max-or-audit-defense-and-now-i-m-being-audited
AUDIT SUPPORT
If you did NOT purchase Audit Defense:
https://support.turbotax.intuit.com/irs-notice/audit-support/
there is no IRS form 4564. clarify. and did you e-file or mail in the return?
It is a general audit request form : https://www.irs.gov/pub/irs-utl/form4564.pdf