You could approach this directly or indirectly. Directly, you speak with your manager. Directly-1): Hey manager, I feel like we haven't been checking in regularly and I'm noticing a lag in email response. I want to make sure I'm executing on your vision to meet our teams goals. Can we meet weekly at our scheduled time? As for day to day communicating, how would you prefer I contact you? In the moment message or email? And if they say email ask, what is a reasonable time to expect a response given your work load. Directly- 2): using data: our 1:1s have been moved or canceled x amt in the last quarter. When i send an email it taking an average of x days to get a response. And then surface the same concern as above. I would gather the data from approach 2 but start with approach one. Indirect 1: Ask a trusted team mate how often they have 1:1s and how quickly emails are responded to. Note the indirect approach won't fix anything. However, if you attempt direct 1 and direct 2 and the issue is not resolved you and your coworkers (who should also bring any concerns to their manager first) could request a skip level with your director. Tell the director as a group that you brought the issue to the managers attention. Have your data ready. And say what you want to happen and why.
But talk to the manager first. And document everything.
Some managers are focused on their team, highly responsive and focused on growth. Others are not for a variety of reasons (disengaged, focused on their on projects/success, being treated as if they don't have a team and being burdened with work that should really be assigned to their team).
Start by assuming they are not aware and then adjust your strategy based on their actions.