Transit visa Dubai while travelling with flydubai

None that are free.

As per their conditions of carriage you are entitled in case of delays:

(b) Unless applicable laws provide otherwise, if your flight is cancelled or delayed for reasons other than outlined in Articles 9.1 and 9.2(a) above the following will apply to you:

(i) if the departure of your flight is delayed less than three hours no compensation or refund will be given;

(ii) if the departure of your flight is delayed more than three hours you will receive a refreshment voucher, applicable to the time of day; and

(iii) if your flight is cancelled you may be re-booked on the next available flight to the same destination free of charge. You can also change the date of your return journey free of charge, subject to availability. Alternatively, you can cancel your reservation and receive a full refund in the form of a Voucher, unless applicable laws provide otherwise.

(c) The three remedies in Articles 9.2(b)(i) to 9.2(b)(iii) do not affect any rights you may have under Article 15.6. Those remedies and rights represent the sole and exclusive remedies and rights available to you if your carriage is affected by one of the events listed in Article 9.2(b).

Or in case of denied boarding:

(a) If you are denied boarding on a flight for which you have a valid Booking Confirmation you will be entitled to travel on the next available flight, receive refreshments and care appropriate to the time of day and duration until the next available flight. You will also receive a refund of the total fare for that sector in the form of a Voucher. You may also change the date of your return journey free of charge once, subject to availability. This does not apply if we refuse to carry you for reasons permitted by these Conditions of Carriage (see, for example, Articles 6 and 7).

(b) If Article 9.3(a) applies to you, we will pay to you any compensation due to you under applicable laws.

(c) Apart from your rights under this Article 9.3, we will have no liability to you for any loss or expense whatsoever.

I suggest you apply for a transit visa (this is not a free service) and then manage your time in Dubai.