Table created with vtable package does not appear

To get rid of the error message, place the caption command outside of the resizebox. Even better would be removing the resizbox alltogether since the use of it on tables will only result in inconsistent font sizes throughtout the document. Additonally, your table already is as wide as the textwidth, so resizebox` does not have any effect here.

In the following MWE, I also replaced the hline commands with lines from the booktabs package, that you already loaded. I also made some commented changes to your preamble:

documentclass{article}
%usepackage[utf8]{inputenc}% not needed any more in a recent installation
%usepackage{graphics}% replaced with graphicx
usepackage{graphicx}
usepackage[export]{adjustbox}
usepackage[margin=1in]{geometry}
usepackage{tikz}
usepackage{booktabs}
usepackage{tabularx}
usepackage{amssymb}

%usepackage{array}% already loaded by tabularx.
usepackage{hyperref} % Should, with just a few exceptions, be the last package in your preamble

begin{document}

begin{table}[!htbp] 
centering 
caption{Summary Statistics}
begin{tabular}{lrrrrrrr}
toprule
Variable & multicolumn{1}{c}{N} & multicolumn{1}{c}{Mean} & multicolumn{1}{c}{Std. Dev.} & multicolumn{1}{c}{Min} & multicolumn{1}{c}{Pctl. 25} & multicolumn{1}{c}{Pctl. 75} & multicolumn{1}{c}{Max}  
midrule
multicolumn{8}{c}{aliado: 0}  
midrule
ano & 36423 & 2008.478 & 4.945 & 2000 & 2005 & 2012 & 2018  
orientacao & 36423 &  &  &  &  &  &   
... Centro & 8337 & 22.9% &  &  &  &  &   
... Direita & 14578 & 40% &  &  &  &  &   
... Esquerda & 13508 & 37.1% &  &  &  &  &   
code & 36423 & 3216561.645 & 971270.128 & 1100023 & 2506103 & 4109302 & 5222302  
code_6 & 36423 & 321655.708 & 97127.013 & 110002 & 250610 & 410930 & 522230  
servico & 36423 &  &  &  &  &  &   
... Água & 26633 & 73.1% &  &  &  &  &   
... Água e Esgoto & 9782 & 26.9% &  &  &  &  &   
... Esgoto & 8 & 0% &  &  &  &  &   
paralisacao_duracao & 9470 & 29.03 & 220.606 & 0 & 6.67 & 14 & 6668.44  
intermitencia_duracao & 5296 & 66.535 & 595.074 & 0 & 3.2 & 13 & 31542.86  
cloro_residual & 28060 & 4.887 & 14.346 & 0 & 0 & 2.24 & 100  
turbidez & 28145 & 7.053 & 17.494 & 0 & 0 & 4.12 & 100  
reparos_esgotos_duracao & 3956 & 12.598 & 41.359 & 0 & 1.85 & 11 & 1213.02  
servico_duracao & 15046 & 53.879 & 289.9 & 0 & 1.03 & 58.373 & 22861.5  
midrule
multicolumn{8}{c}{aliado: 1}  
midrule
ano & 7256 & 2007.959 & 4.923 & 2000 & 2004 & 2012 & 2018  
orientacao & 7256 &  &  &  &  &  &   
... Centro & 3300 & 45.5% &  &  &  &  &   
... Direita & 314 & 4.3% &  &  &  &  &   
... Esquerda & 3642 & 50.2% &  &  &  &  &   
code & 7256 & 3185174.31 & 981385.162 & 1100049 & 2413557 & 4127304 & 5221700  
code_6 & 7256 & 318516.978 & 98138.517 & 110004 & 241355 & 412730 & 522170  
servico & 7256 &  &  &  &  &  &   
... Água & 5809 & 80.1% &  &  &  &  &   
... Água e Esgoto & 1443 & 19.9% &  &  &  &  &   
... Esgoto & 4 & 0.1% &  &  &  &  &   
paralisacao_duracao & 1395 & 36.507 & 247.343 & 0 & 6 & 16 & 4568.29  
intermitencia_duracao & 753 & 66.844 & 714.663 & 0 & 3 & 12 & 18360  
cloro_residual & 5144 & 5.345 & 14.739 & 0 & 0 & 2.872 & 100  
turbidez & 5120 & 8.025 & 17.778 & 0 & 0 & 6.005 & 100  
reparos_esgotos_duracao & 396 & 33.269 & 68.916 & 0 & 2 & 21.088 & 405.98  
servico_duracao & 2516 & 66.857 & 396.499 & 0 & 1 & 49.752 & 14540.2 
bottomrule
end{tabular} %

end{table} 

end{document}