A 64GB device might be adequate if you only ever intend to stream video content - and have no intention of saving material to playback while offline. While your immediately anticipated needs might be adequately served, consider that your requirements may significantly alter during the iPad’s likely lifespan of five to seven years - or longer.
You would be well advised to purchase as much internal storage as your budget might reasonably allow - as internal storage (and other hardware) cannot be changed, upgraded or extended. The available internal storage is fixed for the entire life of the device. If you run out of internal storage for your documents, photos and other data, you will forever struggle and become a source of frustration. It is far better to have more storage than you need, than to need more storage than you have.
A good rule of thumb is to quantify how much data storage you will need - add a healthy margin - then double it. If you are unable to quantify your data storage needs, it becomes more difficult. Whilst I and others cannot cannot make definitive recommendations for your personal needs, objectively I would council against purchase of any iPad with any less than 256GB storage - 128GB perhaps being an absolute minimum.
Within the Apple Support Communities we see regular tales of woe and disappointment when storage requirements are exceeded, necessitating replacement of the device; by contrast, we never see complaint of having too much available storage. It is relatively easy to fill limited internal storage space; perhaps consider higher tiers of storage as providing room for growth as your needs develop or mature - potentially extending the useful usable life of the device.
Consider also the functional differences between WiFi Only and WiFi+Cellularmodels of iPad. Only WiFi+Cellular models include GPS capabilities - which may impact any Apps or features that require accurate and consistent location data, such as Mapping. Purchase of a WiFi+Cellular model does not commit you to using Cellular connections, but provides this flexibility should it be needed. WiFi Only models of iPad have no Cellular or GPS functions at all.
I hope this information and insight proves to be helpful to you.