How to access column in another table through bridged table?

[fatimaarshd]

This is what relationship looks like:

They had many to many relationship but then I created a bridge table Calendar. I need to get number of orders placed the next day. This dax just works fine. TotalPatients =
VAR NextDateInNotifications = MAX('Notifications'[Nudge Date]) + 1
RETURN
CALCULATE(
COUNTROWS(
SUMMARIZE(
FILTER(
ALLSELECTED('Orders'),
'Orders'[OrderCreationDatetime] = NextDateInNotifications
),
'Orders'[CustomerID]
)
)
)

The problem is that I need to count all customers who placed order in a specific category. Now, categories are mentioned in Notification table and not in orders table. I am confused about how to incorporate this? So for instance currently it gives me these counts.For instance if notification was received on 18, and order was placed on 19 then I will get count for 18 like this:

But now I need to add category in it as well. Please guide. 

[andhiii079845]

I think you have to share some sample data. Copy some data samples directly from excel in the textbox. Please so screenshot:)

[andhiii079845]

Can you perhaps upload a better data example and what you want? 
You have bring both tables via the date togehter, so you only will be able to analyize every table for his one. 
You have not ID from the order table in the Notification table. 

[fatimaarshd]

Yes, both of them have customer Ids. 

[andhiii079845]

One idea: bring both table with a composite of the customerID-date together. You can than filter both tables with this combination? I think you have to invest more time in the data modelling topic. 

Perhaps you can merge both tables? 

[fatimaarshd]

Merge isnt working as expected. I am merging both tables using full outer join and it only gives me matched rows and not mismatched rows