Here is the definition of the word ‘contrive’ I found in the OALD:
However, I can’t get it very well. According to the definition, how can anyone ‘decide to contrive’ sth? (‘I decided to succeed in making a meeting between the two of them’?) How can the speaker decide to succeed?
Rather than “succeed in managing”, I would plump for Mister M’s “attempt” + second definition; thus:
I decided to [bring about] a meeting [by a plan, scheme, or the like].
The decision is to make the attempt to do so. As you rightly imply, the example in the dictionary isn’t very good, as it requires a further explanation. It would have been simpler to replace “I decided to contrive” with “I contrived”.