Python doesn't have thunks.
currentnum = int(input('Enter Numbers List, to end enter 0: '))
This sets currentnum to the result of running int on the value returned by the input call. From this point on, currentnum is an int.
while currentnum > 0:
if currentnum > maxx:
max = currentnum
count = 1
elif currentnum == maxx:
count += 1
In this loop, you never take any more input, or reassign currentnum, so the loop will carry on forever, checking the same number over and over again.
If you assigned to currentnum at the end of your loop, you could take input in one-number-per-line. However, you want a space-separated input format, which can be better handled by iterating over the input:
numbers = [int(n) for n in input('Enter numbers list: ').split()]
max_num = max(numbers)
print(f"The largest number is {max_num} (occurs {numbers.count(max_num)} times)")
(Adding the 0-termination support is left as an exercise for the reader.)
Another, similar solution:
from collections import Counter
counts = Counter(map(int, input('Enter numbers list: ')))
max_num = max(counts, key=counts.get)
print(f"The largest number is {max_num} (occurs {counts[max_num]} times)")
I recommend trying your approach again, but using a for loop instead of a while loop.