Trying to Create REGEXP Pattern That Will Detect Numbers Separated by a Space

[theof]

Hi all. I'm trying to create a REGEXP pattern that will check if a string contains a set of numbers separated by a space. I have tried the 4 statements below. They all return 0. What am I doing wrong? Thanks.

SELECT '0630 3062' REGEXP '^[0-9]{4} [[:space:]] [0-9]{4}$';

SELECT 'Employee 346 retrad: 0630 3062' REGEXP '[0-9]{4} [[:space:]] [0-9]{4}';

SELECT 'Employee 346 retrad: 0630 3062' REGEXP '[0-9]+ [[:space:]] [0-9]+';

SELECT 'Employee 346 retrad: 0630 3062 1657 in July Assessment' REGEXP '[0-9]+ [[:space:]] [0-9]+';

The statements are also in this db fiddle

Thanks.