The current Middletown Charter was created by a 1971 Special Act of the NJ Legislature

This special charter is defined in Chapter 237, Laws of 1971, beginning on page 1157

Pages 1164-1168 describes a voter "initiated ordinance": signatures of 25% of registered voters must be obtained (in ink, on paper) in order to submit an "initiated ordinance" to the committee.[NOTE- paper is EXTREMLY LIMITING - PERSONAL DOOR_TO_DOOR COLLECTION IS REQUIRED! Is there NJlegal precidence to allow electronic signatures?]
The Committee then has 60 days to pass the "initiated ordinance".
After 60 days, the clerk will submit the ordinance to the voters at the next general election.
Details are described in Article 5 (pages 1164-1168):

Article 5.8 states: "If within 60 days of the submission of a certified petition by the township clerk the committee shall fail to pass an ordinance requested by an initiative petition in substantially the form requested..., the clerk shall submit the ordinance to the voters.."

There were 51,071 registered voters in Middletown Township, as of the, Nov, 2019 general election
Therefore 12,768 original signatures (and addresses) of Middletown registered voters would be required to submit a voter "initiated ordinance" to the Middletown Committee