The OSM licence (the ODbL 1.0[1]) requires this of the attribution:
> You must include a notice associated with
> the Produced Work reasonably calculated to make any Person that uses,
> views, accesses, interacts with, or is otherwise exposed to the Produced
> Work aware that Content was obtained from the Database, ... and that it
> is available under this License.
i.e. the notice must be such that regular people using this site will know about this.
There must also be a similar notice on the produced map.
> You must include a notice associated with > the Produced Work reasonably calculated to make any Person that uses, > views, accesses, interacts with, or is otherwise exposed to the Produced > Work aware that Content was obtained from the Database, ... and that it > is available under this License.
i.e. the notice must be such that regular people using this site will know about this.
There must also be a similar notice on the produced map.
[1] https://opendatacommons.org/licenses/odbl/1.0/