As @timemage explains in a comment, you cannot pass a capturing lambda to a function that expects a plain pointer to function. There is, however, a way out of this: the Ticker class provides an overload of the attach() method that allows you to provide a parameter of any type to tour callback:

template<typename TArg>
void attach(float seconds, void (*callback)(TArg), TArg arg)

You can use this version of attach() and provide it both

• a non-capturing lambda that get a reference (or pointer) to
•  systemManager that reference or pointer as a third argument.

As @timemage explains in a comment, you cannot pass a capturing lambda to a function that expects a plain pointer to function. There is, however, a way out of this: the Ticker class provides an overload of the attach() method that allows you to provide a parameter of any type to tour callback:

template<typename TArg>
void attach(float seconds, void (*callback)(TArg), TArg arg)

You can use this version of attach() and provide it both

• a non-capturing lambda that gets a pointer to  systemManager
• that pointer as a third argument.

Edit: I did a few tests, and it seems my compiler cannot properly perform template argument deduction in this case, but the approach works if you explicitly specialize the template. Namely:

tickerSystemManager.attach<typeof systemManager>(
    1000,
    [](typeof systemManager p){ p->sync(); },
    systemManager);