There is no such thing as a 32-bit Excel file. Office files don't have bitness. You probably meant you created the Excel file using the 32-bit version of Office. But that doesn't matter for opening the Office document.
Data sources are either x86 or x64 and you use 2 different UIs to set them up. If you simply typed "Data Source" into Windows search then it likely brought up the 32-bit version. You need to use the x64 version to set up the data source if you are using SSRS to connect to it. However the driver has to be installed first. Open the x64 version of data sources and ensure the ACE driver shows up. If it doesn't then you need to install the x64 version of the driver first.
But here's the thing, SSRS is just the server side. If you are building a report then you'll be using a separate tool, likely the VS Shell which is 32-bit. Therefore when you are designing the report you'll be using the 32-bit version of the driver. However when you deploy the report to your SSRS server you'll need to configure the data source in the SSRS Report Manager UI to use the x64 driver. This basically just means opening the data source in the UI and ensuring it properly connects to the source. If both x86 and x64 versions of the driver are installed it should just work.
Please clarify when you are getting the error: When you go into preview mode in the designer, when you attempt to deploy and run the report on the server, etc?
What designer are you using to test with (VS Shell's preview, SSRS Report Manager, etc)?
Have you confirmed in the Data Sources of Windows for both x86 and x64 that the driver is installed?
If you can see the data source while designing/previewing but not when trying to run from the server can you confirm if you can see the data source on the SSRS server?