It seems to go like that:

Take the base64 decoded string and group it like that:

007168 000888 014720 000388 000444 000512 000388 025600 007488 007296 003552 002944 000832 003648 # 63722328665635

Convert these numbers to hex rsp. binary. One sees that these 16 bit numbers are bytes that were left shifted by some amount. Convert these bytes to ASCII and you get [HTML_REMOVED]posao@aduro.hr[HTML_REMOVED].

I don't know what the number after # means, it could encode the shift amount in some way.

007168 = 0x1c00 = 00_01110000_000000 => p

000888 = 0x0378 = 00000_01101111_000 => o

014720 = 0x3980 = 0_01110011_0000000 => s

000388 = 0x0184 = 000000_01100001_00 => a

000444 = 0x01bc = 000000_01101111_00 => o

000512 = 0x0200 = 00000_01000000_000 => @

000388 = 0x0184 = 000000_01100001_00 => a

025600 = 0x6400 = _01100100_00000000 => d

007488 = 0x1d40 = 00_01110101_000000 => u

007296 = 0x1c80 = 00_0111001_0000000 => r

003552 = 0x0de0 = 000_01101111_00000 => o

002944 = 0x0b80 = 00_001011100_00000 => .

000832 = 0x0340 = 00000_01101000_000 => h

003648 = 0x0e40 = 000_01110010_00000 => r

You know that the application time has expired 3 days ago? [HTML_REMOVED]