OpenCycleMap is operated by ThunderForest, a paid service. They overlay the message “API KEY REQUIRED” on their maps to encourage users to register with them.
You can create a free account and update the map definition in MyTrails > Maps > tap on the OpenCycleMap entry and edit the map URL, adding
?apikey=123abc at the end of the existing URL, where
123abc should be replaced with your real API Key.
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