Hello, and welcome.
Gaining the ability to craft ASAM sensors is a part of the story/questline, at least for now (there might be a story-free version of SS2 at some point in the future)
Jake Evans (the Stranger) appears in the first settlement where you build and power a vanilla (only) recruitment beacon, and sometimes he isn't obvious, particularly if you already have settlers roaming around. In Sanctuary, for example, I think there are 4 different spots where he might spawn, and sometimes he makes himself comfortable instead of roaming where you might more easily notice him. If you don't remember which settlement you first powered the beacon in you might try moving to him via console command - I don't recall his ID at the moment, but if he spawned somewhere, that should work (though console commands are best used sparingly since they can have unforeseen consequences).
If he isn't appearing in game for you at all, please confirm that you have everything installed correctly and in the correct load order (check the
wiki for
Requirements,
Installation Guide,
Starting the Mod,
FAQ,
Known Issues,
Troubleshooting, and more).
If you have confirmed that everything is installed and set up correctly and you are certain that he isn't in any of your settlements, you might have a mod conflict. If you post your load order and plug-ins (either as an attachment or under a spoiler tag, please) someone in the community might be able to identify a possible conflict that isn't more broadly known and already logged.